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單項選擇題

When start a screw pump, the by pass valve should be （）.

A.closed
B.opened fully
C.cracked open
D.partly open

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單項選擇題

A centrifugal pump can’t supply water after startingYou should check （）.

A.priming water
B.power supply
C.packing gland
D.bearing lubrication

單項選擇題

Open the （）of inter cooler before starting an air compressor.

A.cylinder cover
B.cooling water
C.oil cup
D.drain valve